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Functional vs. Non-Functional Muscle Hypertrophy

Anyone reading this article is going to need to know what I am talking about first. So what is “functional” muscle hypertrophy? Well… whats the function of a muscle? To contract! Therefore, functional hypertrophy is hypertrophy which results in a direct increase in the amount of force that a muscle can contract with. For those of you who do not know what hypertrophy means… it’s basically a fancy and well defined word for biological growth or increase in size. It is fancy but I like it and will not dumb it down.

Anyways, below is a muscle cell! Important bits to note are the myofibril bundles and the sarcoplasmic reticulum.

What you need to know about the sarcoplasmic reticulum, here after referred to SR, is that it is much like a fuel tank. The SR contains calcium ions, glycogen molecules, creatine phosphate, ATP, myoglobin and many other substances important for muscle contraction. It is important to note that hypertrophy of the SR results in longer possible sustained muscle contraction as it increases the storage of energy molecules (gylcogen, ATP, CP) and molecules important for the continuation of the contraction cycle (myoglobin and calcium). Hypertrophy of the SR is referred to as non-functional hypertrophy because it does not directly increase the force of contraction a muscle fiber is capable of. This hypertrophy is commonly seen in bodybuilders as they generally lift weights with lower weight and high repetitions, increasing their need for greater storage of substances in the SR for prolonged muscle contraction. This tends to result in large, bloated looking muscles. BTW I am not bashing bodybuilders as I respect what they do… but this is how it is.

Functional hypertrophy, or hypertrophy brought on by weight training using heavier weight with low reps and high sets, affects the cross-sectional area and density of the myofibril bundles. It is called “functional” because it directly increases the force at which the muscle fibers can contract. It makes sense that training with heavy weights at low repetitions will influence functional hypertrophy as the limiting factor will be the muscles raw force of contraction and not endurance, its all about where the most stimulus is at. A lot of power/olympic lifters train with this idea in mind because lifting very heavy weights is their sport and objective. It doesn’t matter to them what their endurance is like.

There is no fine line between these two types of hypertrophy and there is a great deal of interaction between the two. Many sports require a balance of these types of hypertrophy as too much of one will most often negatively impact an athletes performance. This is, of course, sport specific, and there are many sports out there.